
function f(a, b) {
    console.log(a); //1
    var a = 123; 
    console.log(a); //123
    console.log(c); //undefind
    function a() { }
    if (false) var d = 678
    console.log(d); //undefind
    console.log(b); //2
    var b = function () { }
    console.log(b); //function
    function c() { }
    console.log(c); //function
}
f(1,2)